This invention relates to a fossil-fired thermal system such as a power plant or steam generator, and, more particularly, to a method to synchronize data obtained from such systems. Particularly this invention relates to how synchronized data is corrected, given that these corrections are needed by established methods which describe, in real time, fuel chemistry, heating value, boiler efficiency, fuel energy flow, L Factors, FC Factors, and/or system heat rate.
The importance of determining a fossil-fired thermal system""s heat rate is critical if practical hour-by-hour improvements in heat rate are to be made, and/or problems in thermally degraded equipment within the system are to be found and corrected (note that heat rate is inversely related to system efficiency as: Heat Rate (Btu/kWh)=3412.1416/Efficiency). Analytical tools are available which allow in real time the determination of related thermal performance parameters. These are described in one or more of the following U.S. Pat. No. 6,522,994 (hereinafter termed ""711 after its application Ser. No. 09/273,711), U.S. Pat. No. 6,584,429 (hereinafter termed ""853 after its application Ser. No. 09/630,853), and U.S. Pat. No. 6,560,563 (hereinafter termed ""956 after its application Ser. No. 09/827,956). ""711 describes calculating in an explicit manner a fuel chemistry and fuel heating value of a fossil-fired thermal system using the Input/Loss Method; said fuel chemistry includes elementary fuel constituents, fuel water and fuel ash concentrations whose explicit computations are principally based on combustion effluents. ""853 describes determining a boiler efficiency of a fossil-fired thermal system using the Input/Loss Method as comprising an Enthalpy of Products term, an Enthalpy of Reactants term, and a Firing Correction term all referenced to the fuel""s calorific temperature. ""956 describes determining a heat rate of the fossil-fired system using the L Factor method as comprising a corrected L Factor, a corrected total effluents mass flow rate and a produced electrical power. However, the process of determining chemistry and heating value of a fossil fuel, such as coal, in real time is strongly dependent on measurements of effluent CO2 and O2, in addition to other xe2x80x9coperating parametersxe2x80x9d defined herein, and also discussed in ""711. Data signals from instrumentation measuring these quantities may often be delayed in time relative to other data due to one or more of the following circumstances: physical measurement techniques; delays in non-uniform storage of data; and/or having an incorrect time stamp associated with the beginning or end of data averaging (versus, for example, a mid-point time or instantaneous time associated with other data).
This invention teaches through data synchronization techniques to correct time delays in data when such data is used to determine fossil fuel chemistry, heating value, boiler efficiency, fuel energy flow and/or system heat rate. Before the advance of technology allowing for such determinations, data synchronization as taught by this invention was not needed. However, established analytical tools employing these technologies, as learned during the course of developing this invention, require correction to achieve acceptable accuracies. Such established analytical tools used to determine fuel chemistry, heating value, boiler efficiency, fuel energy flow, system heat rate, L Factors, FC Factors, and related parameters, are discussed at length in ""711, ""853 and ""956.
Analytical tools commercially available which claim to determine fuel chemistry, fuel heating value, fuel energy flow and/or system heat rate in real time include at least the following: the Input/Loss Method offered by Exergetic Systems, Inc. of San Rafael, Calif.; the OPTIMAX system offered by ABB Power Automation Ltd., Baden, Switzerland; the PMAX system offered by ScienTech, Inc., Idaho Falls, Id.; the L Factor Method offered by Exergetic Systems, Inc. of San Rafael, Calif.; the F Factor Method promoted by the Energy Research Center, Lehigh University, Bethlehem, Penn.; methods promoted by the Center for Electric Power, Tennessee Technological University, Cookeville, Tenn.; and any other method determining fuel chemistry, fuel heating value, fuel energy flow or heat rate in real time for thermal systems burning fossil fuels, and especially for system burning coal fuels. A rudimentary Input/Loss Method is described in U.S. Pat. No. 5,367,470 issued Nov. 22, 1994 (hereinafter termed ""470), and in U.S. Pat. No. 5,790,420 issued Aug. 4, 1998 (hereinafter termed ""420).
There is no known art to the present invention. None of the aforementioned commercial offerings, nor ""470 and ""420, nor ""711, ""853 and ""956 and their related provisional patent applications and Continuation-In-Parts, teach any corrective techniques leading to data synchronization as is important when determining fossil fuel chemistry on-line. None of the aforementioned promote nor advance the idea that data synchronization is even required at the conceptual level. For situations involving power plant or steam generator monitoring using the Input/Loss Method, or similar method, but not addressing data synchronization the accuracy and performance of such methods may be flawed.
In applying the teachings of ""711 and ""956 at coal-fired power plants, it has become apparent in developing the methods of this invention that the on-line determination of fuel chemistry and/or fuel heating value is highly sensitivity to effluent measurements, and to their relative consistency in time to each other, that is data with the same time stamp (i.e., the same identifying reference time). The work of this invention has found that data synchronization must be an important consideration when determining fuel chemistry of a fossil-fired thermal system in real-time, and especially as related to the system""s operating parameters including effluent measurements. Of these, CO2, H2O and O2 measurements, following ""711 discussion of how these measurements may be obtained, are the most important. However, the methods as taught herein may be applied to all data involved in determining fuel chemistry, fuel heating value and/or system heat rate including the Input/Loss Method.
Data synchronization is especially important if CO2, H2O and O2 measurements have different time delays. An increase in CO2, other parameters remaining approximately constant, implies a decrease in effluent O2. However, delays in one of these signals, if not corrected, could easily create a situation where both CO2 and O2 signals appear to increase or decrease together as would be observed by an uncorrected data acquisition process. The H2O is taken herein to be either directly measured at the system""s boundary, or otherwise determined. As an example of such sensitivity obtained from a coal-fired power plant, and using methods of ""711, consider that a 1.5 minute delay in a CO2 signal resulting in a 1.0% xcex94mole/mole change, results when averaging data over two minutes in a 2.7% change in computed heating value. If mis-diagnosed in computing a change in heat rate (254 xcex94Btu/kWh), assuming a typical worth of $30,000/xcex94Btu/kWh/year, this 1.0% sensitivity to delays in data collection is worth $7.62 million/year.
When the monitoring a fossil-fired thermal system involves real time analytical modeling of the fuel being burned, and when such modeling relies in part on effluent measurements, this invention recognizes a strong dependency on the synchronization of effluent CO2, H2O and O2 measurements. This invention recognizes that effluent CO2, H2O and O2 measurements must be consistent in time. As taught by ""711 the determination of fuel chemistry, fuel heating value and/or fuel energy flow, dependent principally on effluent CO2, H2O and O2 measurements, are not dependent on measured fuel flow. As taught by ""956 the determination of fuel energy flow, when dependent on effluent CO2 measurements, may not be dependent on fuel flow. However, fuel flow is dependent, in part, on working fluid energy flow. Fuel energy flow is determined when fuel flow is multiplied by fuel heating value (fuel energy flow having typical units of Btu/hour). System heat rate is determined when fuel energy flow is divided by a system""s power production (system heat rate having typical units of Btu/kWatt-hour). Effluent CO2, H2O and O2 measurements typically have a physically different data acquisition system (typically central to the placement of these instruments, near the smoke stack), from the system""s traditional data acquisition system whose data is used to determine working fluid energy flow. As such, possible time delays in the acquisition of data is not uncommon, and must be considered such that synchronization of data is achieved; from which consistent heat rate may then be determined.
This invention teaches a method for quantifying the operation of a fossil-fired thermal system in which its fuel chemistry, fuel heating value and/or fuel energy flow are being determined by analytical models using system data, whereas the method includes the steps of first obtaining collections of system data, each collection consisting of individual data points. Second it allows for the determination of time delays associated with the individual data points. The method then determines a synchronous and consistent collection of data dependent on time delays associated with the individual data points and the collections of system data. This synchronous collection of data may then be input to analytical models which determine one or more of the following quantities of the fossil-fired thermal system: fuel chemistry, fuel heating value, boiler efficiency, fuel energy flow, and/or system heat rate.